IN A BID TO save the critically endangered quoll, ecologists from The University of Sydney have found a new way to outsmart cane toads.

Quolls are small carnivorous marsupials under threat of extinction because of their tendency to eat toxic cane toads. The last stronghold of the northern quoll, in Western Australia’s Kimberly regions, will soon be invaded by cane toads and conservationists fear for the survival of the species.

The study, led by Professor Rick Shine, tested whether northern quolls could be taught to avoid eating cane toads through a process called conditioned taste aversion. "Taste aversion can be incredibly long-lasting" says Rick. "I drank too
much scotch when I was 18; I'm 60 now and haven't touched it since."

Taste aversion

In the research, a sample of quolls were fed dead cane toads injected with a nausea inducing chemical before being released into the wild. The researchers monitored their progress in the natural environment and found that the toad-smart quolls survived up to five times longer than their "toad-naive" counterparts. The research is published this week in the Journal of Applied Ecology.

Like humans, animals will learn quickly to survive. The problem is that cane toads are so poisonous that predators rarely have a second chance. "Large predators are the big victims," he says. "If you take the top predators out of an ecosystem, this will have a drastic impact on the natural biodiversity."

Rick and his co-workers are confident that quolls, along with other predators, can survive in a toad-infested landscape if they are taught to avoid cane toads.

Wider implications

The project also has wider implications for other species, says University of Sydney biologist Mike Letnic. Mike has studied the impact of cane toads on freshwater crocodiles: “[The project] has the potential to protect crocodiles and quolls. But the issue is how to deliver the baits.”

Since their introduction in 1935, cane toads have wrought havoc on Australia’s native wildlife. Despite this, it was only in 2005 that they were listed as a‘Key Threatening Process’ by the Department of the Environment and Heritage because of their damaging impact on the northern quoll population.